The U.S. Department of the Interior shared video of thousands of tree swallows lifting off in unison at a federal wildlife refuge north of Boston, a spectacle the agency compared to a tornado.

The footage, posted Tuesday, captures what the department called a "birdnado" at the Parker River National Wildlife Refuge Complex in Newburyport, Massachusetts. Massive flocks of tree swallows swirl skyward from the refuge's marshlands during their annual fall migration, creating a dense, twisting column of birds that looks more like a weather event than a wildlife one.

The refuge sits on the North Shore of Massachusetts, about 35 miles north of Boston off the Plum Island Turnpike. Its more than 4,700 acres of wetlands, beaches, dunes, forests, salt marshes, and mud flats make it prime habitat for birds heading south before winter, and a reliable draw for birdwatchers and photographers year-round.

Why thousands of swallows pile into one spot every fall

Tree swallows are among the most common nesting birds in Massachusetts. During summer, Mass Audubon notes, they can be seen by the hundreds perched atop telephone wires near the shore. But the real show comes in autumn, when enormous flocks gather along the coast before pushing south to wintering grounds that stretch from the southern United States into Central America.

Parker River's marshes offer exactly what the birds need: insects and berries for fuel, and open ground for rest. When enough swallows converge on the refuge at once, the result is the swirling mass the Interior Department captured on video.

The department leaned into the moment with a quip alongside the footage:

"When enough swallows show up at once, migration starts looking a lot like Twister... the original... not the remake."

A 50-year-old refuge built for exactly this

Parker River National Wildlife Refuge was established in 1971 as a federal conservation area. More than 300 species of birds have been documented there, including federally protected piping plovers. The refuge is open to the public every day from sunrise to sunset.

For anyone who has never visited, it is the kind of quiet, publicly accessible land that federal conservation dollars were meant to protect, and the kind of place where nature occasionally puts on a show that no budget line can plan for.

Washington spends plenty of time arguing over land use and agency budgets. Moments like this one are a reminder of what those acres actually produce when left to do their job.